Apparatus and method for dehydrating wet particulate matter and for disposing of waste products therefrom

ABSTRACT

Apparatus and method for two-stage dehydration of wet particulate matter (such as green forage chops) and disposition of waste products produced during the second stage of dehydration, such as gases, smoke and charred particles, comprise: a first furnace for firing a first dryer in which the chops are partially dried; a first dryer fan for drawing the chops through the first dryer and for disposing of hot moist air; a second furnace for firing a second dryer in which the chops are finally dried and wherein the waste products are produced, the second dryer having a smaller air-handling capacity than the first dryer; transfer means for delivering the partially-dried chops from the first dryer to the second dryer and including either a first cyclone separator connected to the first dryer fan or a material discharge hood disposed between the first dryer and the first dryer fan and a conveyor connected to the discharge hood; a second dryer fan for drawing the chops through the second dryer; a second cyclone separator connected to the second dryer fan for separating the finally-dried chops from the aforesaid waste products; and means, including a conduit and booster fan, for delivering the aforesaid waste products from the second cyclone separator to the first furnace wherein they are consumed.

llnited States Patent 1 Arnold [76 Inventor: William A. Arnold, 2415 S.65th St.,

W. Allis, Wis. 53214 [22] Filed: Sept. 15, 1971 [21] Appl. No.: 180,702

' [52] U.S. Cl. 432/106, 432/15, 432/58,

34/10, 34/136, 34/140 [51] Int. Cl. F26b 7/00, F27b 7/00 [58] Field ofSearch 263/32 R, 21 A, 21 B;

[56] References Cited UNITED STATES PATENTS 2,997,286 8/1961 Friese432/15 2,987,306 6/1961 Petersen 432/15 2,770,052 11/1956 Morrison432/15 2,822,153 2/l958 Arnold 432/106 3,603,568 9/1971. Ritzmann....432/58 3,238,634 3/1966 Goins 34/10 999,492 8/1911 Ellis 263/32 R3,387,380 6/1968 Pritts, Jr 263/32 R Primary Examiner-John J. CambyAssistant Examiner-Henry C. Yuen Attorney-James E. Nilles and Thomas F.Kirby 11 3,738,790 [4 1 June 12, 1973 [57] ABSTRACT Apparatus and methodfor two-stage dehydration of wet particulate matter (such as greenforage chops) and disposition of waste products produced during thesecond stage of dehydration, such as gases, smoke and charred particles,comprise: a first furnace for firing a first dryer in which the chopsare partially dried; a first dryer fan for drawing the chops through thefirst dryer and for disposing of hot moist air; a second furnace forfiring a second dryer in which the chops are finally dried and whereinthe waste products are produced, the second dryer having a smallerair-handling capacity than the first dryer; transfer means fordelivering the partially-dried chops from the first dryer to the seconddryer and including either a first cyclone separator connected to thefirst dryer fan or a material discharge hood disposed between the firstdryer and the first dryer fan and a'conveyor connected to the dischargehood; a second dryer fan for drawing the chops through the second dryer;a second cyclone separator connected to the second dryer fan forseparating the finally-dried chops from the aforesaid waste products;and

means, including a conduit and booster fan, for delivering the aforesaidwaste products from the second cyclone separator to the first furnacewherein they are consumed.

14 Claims, 6 Drawing Figures PAIENIED Jun 1 2191s smzennr FIG.1

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates generally to apparatus and methods for two-stage dehydration ofwet particulate matter, such as forage material or chops, and fordisposing of waste products, such as gases, smoke and charredparticulate material, produced during the second stage of dehydration.

2. Description of the Prior Art In agriculture, for example, it is thepractice to harvest forage crops, such as alfalfa or the like, and todry the leaves and stems (in chopped or unchopped form) by means ofdehydration apparatus which removes all but about 8 percent of themoistureand leavesa concentrated, uniform feed product. Some prior artdehydration apparatus comprises an oil or gas-fired furnace whichexhausts hot air (typically up to about 2,000 F.) into a dryer whichcomprises a rotating sealed drum through which the matter to be dried ispassed. The material in the drum continually gives off moisture and,

discharge end of the drum, removes hot, moist gases and also advancesthe matter through the drum and dis- 'charges it into a first cycloneseparator. The stems,- which are moister and heavier than the leaves andrequire more drying time, automatically move more slowly through thedrum. A second fan transports the dried matter from the first cycloneseparator to a second cyclone separator, cooling and further drying itin the process. The dried cooled matter is removed from the secondseparator and is then ground or pelleted, bagged and stored. A foreignmaterial separator is provided at the outlet end of the first cycloneseparator to remove debris such as stones and tramp metal. Vents at thetop of the first and second cyclone separators allow hot, moist gases,fine particulate matter and other waste products extracted by the dryerfan and the cyclone or cooler fan, respectively, to be discharged toatmosphere. I I

While such priorart dehydration apparatus is generally satisfactory forits intended purpose, the exhaust to atmosphere from the cycloneseparators is a source of objectionable odors, fine particulate matter,and sometimes smoke. and other gases produced in the dryer which mayviolate pollution codes or otherwise be offens ive. Formerly, theseodors and fines could only be eliminated by means of inefficientafter-burners or high-cost heat exchangers. It is desirable, therefore,to provide improved dehydration apparatus and methods which eliminatethe aforesaid problems and have other advantages.

SUMMARY OF THE INVENTION supplied with heat from the second furnace,transfer partially dried matter from the first dryer to the seconddryer, a second dryer fan connected to the discharge end of the seconddryer, means including a second cyclone separator connected to thesecond dryer fan for separating finally-dried matter from wasteproducts, such as gases, smoke and charred particles, and meansincluding a conduit connected between the second cyclone separator andthe furnace means for delivering the waste products to the furnace meansfor combustion. In accordance with a second embodiment of the invention,a discharge hood is connected between the discharge end of the firstdryer and the first dryer fan and the transfer means comprise a conveyorconnected between the hood and the second dryer.

The method in accordance with the invention comprises the steps Of:supplying wet particulate matter to the first dryer and partially dryingit; drawing the matter through the first dryer by means of the firstdryer fan and exhausting water vapor extracted; transporting thepartially-dried matter from the first dryer and supplying it to thesecond dryer by means of either the first cyclone separator or by theconveyor; drawing the partially-dried matter through the second dryerwherein it is finally dried and delivering the finally-dried matter tothe second dryer cyclone by means of the second dryer fan; separatingthe finally-dried material from the waste products produced in thesecond dryer in the second dryer cyclone; discharging the finally-driedmaterial from the second dryer cyclone for further processing; andsupplying all of the escaping waste products produced in the seconddryer and in other stages of processing to the furnace means forincineration.

Other aspects of the invention provide improved apparatus and methods(I) for dehydrating wet particulate matter and for disposing of wasteproducts produced during dehydration; (2) which employ two furnace-fireddryers operating in tandem and wherein waste products produced in thesecond dryer, such as gases, smoke and charred particles, are consumedin the furnace means; (3) which are applicable to treat many kinds ofwet particulate matter and which substantially reduce or eliminatepolluting by-products produced during treatment; (4) which do notrequire the use of inefficient after-burners or high-cost heatexchangers; (5) wherein the furnace means use a minimum amount of fueland wherein fuel requirements are supplemented by combustible wasteproducts thereby means including a first cyclone separator for supplyingreducing fuel costs; (6) wherein the first dryer makes maximum use ofheat supplied thereto because matter therein is only partially dried,which means low o'utlet temperatures of the exhaust gases from the firstdryer for maximum thermal efficiency; (7)'wherein operation of the firstdryer is at temperatures as high as possible commensurate with the wetmatter thereby achieving minimum or no scorching of the matter duringthe first drying stage and minimum or no production of objectionablecharred fines, smoke and odors; (8) wherein final drying in the seconddryer is carried out at relatively lower temperatures to achieve minimalscorching or other damage during the second stage of drying; and (9)wherein any fines produced by the first dryer are recoverable anduseful.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view in schematicform of one embodiment of two-stage hydration apparatus in accordancewith the invention;

FIG. 2 is an elevational view of a portion of the apparatus shown inFIG. 1 and principally shows a first furnace, a first dryer, a firstcyclone separator and a portion of a second cyclone separator;

FIG. 3 is a view taken along lines 33 of FIG. 3 and principally showsthe first dryer, a supply feeder therefor, and the first cycloneseparator;

FIG. 4 is an elevational view taken along lines 44 of FIG. 1 and showsthe second cyclone separator;

FIG. 5 is a top plan view of portions of a second embodiment ofapparatus in accordance with the invention and shows a discharge hoodand conveyor; and

FIG. 6 is a cross-sectional view of the discharge hood taken along lines66 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1, 2 and 3of the drawing, there is shown a first embodiment of a dehydrationapparatus in accordance with the present invention which is used to drywet particulate matter, such as freshly-harvested chopped alfalfa(hereinafter referred to as chops). The first embodiment comprisesfurnace means including a first furnace 10 having a burner assembly 12and a combustion chamber 14. The burner assembly 12 is understood tooperate on either gas, coal, oil or other suitable fuel which is burnedin combustion chamber 14 to supply a quantity of heated air in thetemperature range of about l,0O0 to 2,000 F. to a first dryer 16. Burnerassembly 12 is controlled by a thermostat 18 which senses airtemperature at the discharge outlet of first dryer 16 and regulatesburner 12 accordingly, as regards fuel and air, to maintain a constantdesired temperature at the discharge outlet of the first dryer. Burnerassembly 12 and combustion chamber 14 are designed so that exhaustproducts therefrom are kept at a minimum and they burn clean.

First dryer 16 is shown in the drawings as a rotatable drum type dryerbut it is to be understood that dryer 16 could be any type of encloseddryer such as, for example, a flash-type dryer or a conveyor-type dryerwherein a conveyor is used to move material through a fixed enclosure.

First dryer 16 may be of the single pass or multiple pass type. However,as FIG. 2 shows, first dryer 16 takes the form of a multiple pass type.First dryer 16 comprises a rotatable drum 20, suitable bearing means 22for supporting the drum for rotation, and an electric motor 24, a powershaft 26, a chain drive 28, and a rotation gear 30 for rotating thedrum. Drum is provided on its interior with a series of interconnectedpassages 32 through which the chops pass in traveling from a wet feedinlet 34 of the drum to a discharge outlet 36. In the embodiment shown,it is understood that the chops pass through a distance approximatelythree times the overall length of the drum. Chops are supplied to inlet34 of first dryer 16 by means of a conveyor 37 which is supplied from achopper 38, shown in FIG. 3. Chopper 38 and conveyor 37 are powered, forexample, by a drive belt 40, shown in FIG. 3, which is ultimately drivenby motor 24, shown in FIG. 2, through suitable power take-off means.

Outlet 36 of first dryer 16 is connected to a first dryer fan 42 whichcreates an air flow and serves as a means to draw the chops through thepassageways 32 in drum 20, as well as to draw hot, moist air from thedryer. First dryer fan 42 is driven, for example, by an electric motor43. A discharge outlet 44 of first dryer fan 42 is connected through aconduit 46 to an upper inlet 48 of a first cyclone separator 50. Chopsand hot, moist air drawn from dryer 16 by first dryer fan 42 areexpelled into cyclone separator 50. The hot, moist air is discharged toatmosphere through a vent 52 at the top end of cyclone 50 and the chopsfall to the bottom of cyclone separator 50 from whence they aredischarged by gravity through a conduit 54. It is to be understood thatthe chops are only partially dried in first dryer 16 and, consequently,the only waste product produced is hot, moist air which is discharged toatmosphere as hereinbefore explained. In practice, it is contemplatedthat about to percent of the moisture be removed from the chops inpassing through first dryer 16 and the temperature of the chops in thefirst dryer averages, for example, about F. in the case of alfalfa and,consequently, no charring or burning or smoke is produced.

As FIG. 1 further shows, the furnace means for dehydration apparatus inaccordance with the first embodiment comprises a second furnace 56having a burner assembly 58 and a combustion chamber 60. Structurally,second furnace 56 is similar to first furnace 10; however, secondfurnace 56 is smaller and adapted to provide hot air heated only to arange of about 500 to 1,000 F. to a second dryer 62. Second furnace 56is controlled by a thermostat 64 similar to thermostat 18 hereinbeforedescribed. In practice, both thermostats and both furnaces are adjustedso that the system is balanced to provide a desired percentage of dryingin each of the dryers. It is to be understood that second furnace 56also burns clean and provides no substantial waste products toatmosphere.

Second furnace 56 is adapted to supply hot air to second dryer 62 whichis similar in construction and operation to first dryer 16, except ashereinafter explained. Dryer 62, which like dryer 16 could be anysuitable type of enclosed dryer, could also be of the single pass ormultiple-pass type, but is shown in the drawings to comprise a rotatabledrum 63 having an air-handling capacity which is substantially smallerthan the airhandling capacity of drum 20 of dryer 16. .For example, drum63 of dryer 62 may be considered to have an airhandling capacity ofabout only one-third to one-half of that of drum 20 of first dryer 16.Drum 20 of second dryer 62 has a feed inlet 66 to which is connected thedischarge end of conduit 54 from cyclone separator 50 andpartially-dried chops are supplied to dryer 62 by gravity feed.Partially-dried chops enter dryer 62 at substantially the sametemperature at whichthey left first dryer 16, i.e., about 150 F. in thecase of alfalfa. In the course of passage through second dryer 62, forexample, all but about 2 to I5 percent of the moisture is removed fromthe chops. In addition, charring of some of the chops occurs because thechops are no longer as wet as when passing through first dryer l6 and,consequently, waste products such as smoke, gases and charred particlesmay be produced in second dryer 62.

Second dryer 62 is provided with a discharge outlet 70 to which a seconddryer fan 72 is connected. Second dryer fan 72, which is driven by anelectric motor 72, may be similar in construction and operation to firstdryer fan 42, hereinbefore described, and serves as a means to move thechops through second dryer 62 and also to remove the waste productsproduced in second dryer 62. Second dryer fan 72 has a discharge outlet75 connected to a second cyclone separator 76 and discharges thefinally-dried chops, as well as all waste products, thereinto.

Referring to FIGS. 1', 2 and 4, second cyclone separator 76 is providednear its top with a discharge vent 78 which is connected through anenclosed conduit or pipe 80 to combustion chamber 14 of first furnace10. Second cyclone separator 76 is also provided with a discharge outlet82 at its lower end, as FIG. 4 shows. The finally-dried chops settle tothe bottom of second cyclone separator 76 and pass through dischargeoutlet 82 by gravity into a hammermill 84 or other device for furtherprocessing or final disposition. However, the waste products produced insecond dryer 62 are discharged through discharge vent 78 in secondcyclone separator 76 and through conduit 80 to combustion chamber 14 offirst furnace wherein they are consumed. As FIG. 2 shows, conduit 80 hasa booster fan 86, driven by an electric motor 88, connected to it justupstream of the point where it is connected to combustion chamber 14 offurnace 10. Booster fan 86 causes dispersion of waste products enteringcombustion chamber 14, especially solid particles present in the wasteproducts, and thereby assures complete combustion. As FIGS. 1, 2 and 4show, conduit 80 is also provided with an auxiliary waste material inletduct 90, possibly having a control damper 92 therein (shown in FIG. 1),through which other waste products may be introduced. For example,auxiliary inlet duct 90 maybe connected to an outlet 94 on hammermill 84(shown in FIG. 4) to receive waste material, such as fines and dust,which are produced in the hammer mill. These waste materials are alsothen consumed by furnace 10 and do not contaminate the atmosphere. It isto be understood that burner 12 of furnace 10 is adjusted so as r toallow for entry of such makeup air as is necessary to ensure completecombustion of all products entering combustion chamber 14 throughconduit 80, either from cyclone separator 76 or auxiliary inlet duct 90or both. I

Referring to FIGS. 5 and 6, there is shown an alternative or secondembodiment of dehydration apparatus in accordance with the presentinvention wherein partially-dried chops from discharge outlet 36 offirst dryer 16 are delivered to inlet opening 66 of second dryer62 byconveyor means 100, instead of by means of first cyclone separator 50.As FIG. 5 shows, conveyor means 100 comprises a discharge hood 102 whichis located between discharge outlet 36 of first dryer l6 and first dryerfan 42. Partially-dried chops from first dryer 16 are drawn into anddeposited in discharge hood 102 by r the action of first dryer fan 42.Hot, moist vapor drawn from first dryer 16 is discharged through cycloneseparator 50'to atmosphere through vent 46 on first dryer fan 42, shownin FIG. 5. In the process, some fines and rator 50 can be removed. Insome instances, such material may be sufficiently dry and can betransported directly to hammermill 84 without having to undergo thesecond stage of drying in dryer 62. The partially-dried chops aretransported or conveyed from discharge hood 102 to inlet opening 66 ofsecond dryer 62 by means of a mechanical conveyor 104 which comprises ahousing 106 and a rotary auger 108, for example, which is driven by anelectric motor 110.

The dehydration apparatus, in accordance with the first embodiment ofthe invention, operates as follows. Wet chops are introduced at inlet 34of first dryer 16, pass therethrough and are extracted by first dryerfan 42 through outlet 36 of the first dryer and are delivered to firstcyclone separator wherein the partially-dried chops fall to the bottomof the separator and the hot, moist vapors are discharged throughoutlet52 of the first cyclone separator. However, in accordance with theinvention, the partially-dried chops pass by gravity through conduit 54to inlet 66 of second dryer 62. The partially-dried chops are drawnthrough second dryer 62 for the final drying process by second dryer fan72. Second dryer fan 72 withdraws the finally-dried chops and wasteproducts through discharge outlet of second dryer 62 and discharges thefinally-dried chops and the waste products into second cyclone separator76. The finally-dried chops fall to the bottom of second cycloneseparator 76 and pass through discharge opening 82 thereof to ahammermill 84 wherein they are further processed. If preferred at thisstage, the finally-dried chops could be delivered to processingequipment other than to a hammermill 84. Waste products separated fromthe finally-dried chops in second cyclone separator 76 pass throughconduit and are delivered to the combustion chamber of first furnace 10wherein they are consumed. Other waste products produced during variousstages of handling and processing of the partially-dried or fully-driedchops are delivered through auxiliary conduit to conduit 80 for consumption in furnace 10.

As hereinbefore explained, temperatures within first dryer 16 are ashigh as possible commensurate with the wet material being supplied tothe dryer so as to extract the desired percentage of moisture withoutcausing burning or charring of the material. Finish or final drying insecond dryer 62 is carried out at relatively low temperatures whicheffect the required percentage of finish drying with a minimum ofscorching and burning. Since first furnace 10 is operating at relativelyhigh temperature, all waste products introduced into it will alsintroduced through auxiliary conduit 90. As is apparent, supplying ofadditional combustible'materials to first furnace 10 slightly reducesthe amount of gas, oil or other regular fuel required for burner 12. Asregards second furnace 56, it-is to be understood that it receives onlyfresh combustion air and fuel such as gas or oil and it isthermostatically controlled so as to assure a uniform moisture contentin the finished product produced in second dryer 62. It is to be furtherunderstood that first furnace 10 and first dryer 16 are of greatercapacity than second furnace 56 and second dryer 62, respectively,because of the discharge of waste products for combustion into firstfurnace l0 and the need to insure complete incineration.

Dehydration apparatus in accordance with the second embodiment of theinvention operates as follows. Partially-dried material from first dryer16 is drawn into discharge hood 102 by means of first dryer fan 42 anddeposited in the bottom of the discharge hood. The hot, moist vaporsproduced in first dryer 16 and some fines and some partially-driedmaterial are discharged by first dryer fan 42 through conduit 46 tocyclone separator 50. At this point, the partially-dried chops may beremoved from cyclone separator 50 through outlet 55 for finaldisposition. Partially-dried material is deliv-' ered or transportedfrom discharge hood 102 through conveyor 104 to inlet 66 of second dryer62 by driven auger 108. it is to be understood that drying operations infirst dryer l6 and second dryer 62 are carried out in substantially thesame manner as hereinbefore explained in connection with the descriptionof operation of the first embodiment of the invention. The principaladvantage of using conveyor means 100 in accordance with the secondembodiment of the invention is that dried chops collected in dischargehood 102 and passing through conveyor 104 may be exposed to ambient air,not experienced when passing through first cyclone separator 50 in thefirst embodiment of the invention. Consequently, the exposure of thepartially-dried chops to ambient air permits a soaking period or allowsfor equalization of moisture in the partially-dried chops before theyenter second dryer 62. This soaking period may or may not be ofparticular advantage depending upon the material being processed.

While the present invention is hereinbefore described with alfalfa chopsas an example of the wet particulate matter being processed, it is to beunderstood that the invention could be employed with other wetparticulate materials produced in agricultural operations or in varioustypes of manufacturing operations wherein materials other than feedproducts are prothe invention disclosed herein show the furnace means ascomprising two separate furnaces, l and 56, it is to be understood thata single furnace having means to supply the desired amount of heat toeach of the dryers l6 and 62 could be employed. In such an arrangement,for example, first furnace could be provided with a heat take-off forsupplying dryer 62 with heated air which is tempered to the desiredtemperature range with ambient air by means of suitablethermostaticallycontrolled dampers.

In summary, the apparatus and method for two-stage dehydration of wetparticulate matter and disposition of waste products produced during thesecond stage of dehydration contemplates furnace means such as a firstfurnace 10 for firing first dryer 16 in which the wet matter ispartially dried; first dryer fan 42 for drawing the matter through firstdryer 16 and for disposing of hot, moist air; furnace means such as asecond furnace 56 smaller than furnace 10 for firing second dryer 62smaller than dryer 16 in which the partially-dried matter is finallydried and wherein the waste products are produced; transfer means fordelivering the partiallydried matter from first dryer 16 to second dryer62 and including either first cyclone separator 50 connected to firstdryer fan 42 or discharge hood 102 connected to first dryer fan 42 andconveyor 104 connected to discharge hood 102; second dryer fan 72 fordrawing the matter through second dryer 62; second cyclone separator 76connected to second dryer fan 72 for separating the finally-driedmaterial from the waste products; and means, including conduit 80 andbooster fan 86,

for delivering the waste products from second cyclone 6 1. Apparatus fordrying wet particulate matter and for disposing of waste productsproduced during drying comprising:

a first dryer for partially dryer said matter,

means for moving said matter through said first dryer,

a second dryer for finally drying partially-dried matter received fromsaid first dryer, said second dryer producing combustible waste productsduring the final drying of said matter as a result of processing of saidmatter therein,

means for moving said matter through said second dryer, said first andsecond dryers being enclosed type dryers and wherein said second dryeris of smaller air handling capacity than said first dryer, said seconddryer having an air handling capacity in the range of about one-third toone-half of said first dryer,

transfer means for transferring said partially-dried matter from saidfirst dryer to said second dryer,

furnace means for supplying heat to said first and second dryers,

separating means for separating said finally dried matter from saidwaste products, and means for delivering said waste products to saidfurnace means wherein they are consumed.

2. Apparatus according to claim 1 wherein said furnace means maintainsair inlet temperatures within said first and second dryers of aboutl,000 to 2,000 F. and of about 500 to l,000 F., respectively.

3. Apparatus for drying wet particulate matter and for disposing ofwaste products produced during drying comprising:

a first dryer for partially drying said matter,

first means for moving said matter through said first dryer,

a first dryer fan for disposing of moisture released in said firstdryer,

a second dryer for finally drying partially-dried matter received fromsaid first dryer, said second dryer producing combustible waste productsduring the final drying of said matter,

second means for moving said matter through said second dryer,

said first and second dryers being enclosed-type dryers and wherein saidsecond dryer is of smaller airhandling capacity than said first dryer,said second dryer having an air-handling capacity in the range of aboutone-third to one-half of said first dryer,

transfer means for transferring said partially-dried matter from saidfirst dryer to said second dryer,

furnace means for supplying heat to said first and second dryers,

said furnace means maintaining inlet air temperatures in said first andsecond dryers of about l,O00 to 2,000 F. and of about 500 to 1,000 F.,respectively,

separating means for separating said finally-dried matter from saidwaste products and for delivering the latter to said furnace meanswherein they are consumed, and

a second dryer fan for delivering said waste products from said seconddryer to said separating means.

4. Apparatus according to claim 3 wherein said furnace means comprisesfirst and second furnaces for said first and second dryers,respectively.

5. Apparatus according to claim 3 wherein said separating means includesa cyclone separator connected to receive said finally-dried matter andsaid waste products from said second dryer and a conduit connected tosaid cyclone separator for delivering said waste products to saidfurnace means.

6. Apparatus according to claim 5 wherein said first A means for movingsaid matter through said first dryer comprises said first dryer fan.

7.'A pparatus according to claim 6 wherein said transfer means comprisesa second cyclone separator connected between said first dryer fan andsaid second dryer. l

8; Apparatus according to claim 6 wherein said transfer means comprisesa discharge hood connected between said first dryer and said first dryerfan and further comprises conveyor means connected between saiddischarge hood and said second dryer.

9. Apparatus according to claim 8 including a cyclone separator forreceiving fines and some matter from the discharge outlet of said firstdryer fan.

10. Apparatusaccording to claim 6 wherein said second means for movingsaid matter through said second dryer comprises said second dryer fan.

11. A method of drying wet particulate matter and of disposing of wasteproducts produced during drying comprising the steps of:

providing a source of heat by burning combustible fuel in a furnacemeans, partially drying said matter in a first dryer heated by saidfurnace means by maintaining inlet air temperatures in said first dryerin the range from about l,000 to 2,000 F. so as to extract from about 80percent to 90 percent of the moisture to be removed from said matter,

removing moisture from said first dryer and discharging it toatmosphere,

removing the partially-dried matter from the first dryer andtransporting it to a second dryer which is heated by said furnace meansand has a smaller air-handling capacity than said first dryer,

finally drying said partially-dried matter in said second dryer bymaintaining inlet air temperatures in said second dryer in the rangefrom about 500 to 1,000 F. so as to extract all but about 2 per cent to15 per cent of the remaining moisture from said matter and producingcombustible waste products in so doing,

removing the finallydried matter and waste products from said seconddryer and separating them, and conducting the waste products to saidfurnace means wherein they are consumed.

12. A method according to claim 11 including the step of adding makeupair to said furnace means.

13. A method according to claim 12 including the step of tempering theheated air supplied to said second dryer with ambient air so as tomaintain air temperature in said second dryer in the said range.

14. A method according to claim 11 including the step of transportingthe partially-dried matter from said first dryer to said second dryer toallow for equalization of the moisture in the partially-dried matter.

1. Apparatus for drying wet particulate matter and for disposing ofwaste products produced during drying comprising: a first dryer forpartially dryer said matter, means for moving said matter through saidfirst dryer, a second dryer for finally drying partially-dried matterreceived from said first dryer, said second dryer producing combustiblewaste products during the final drying of said matter as a result ofprocessing of said matter therein, means for moving said matter throughsaid second dryer, said first and second dryers being enclosed typedryers and wherein said second dryer is of smaller air handling capacitythan said first dryer, said second dryer having an air handling capacityin the range of about one-third to one-half of said first dryer,transfer means for transferring said partially-dried matter from saidfirst dryer to said second dryer, furnace means for supplying heat tosaid first and second dryers, separating means for separating saidfinally dried matter from said waste products, and means for deliveringsaid waste products to said furnace means wherein they are consumed. 2.Apparatus according to claim 1 wherein said furnace means maintains airinlet temperatures within said first and second dryers of about 1,000*to 2,000* F. and of about 500* to 1,000* F., respectively.
 3. Apparatusfor drying wet particulate matter and for disposing of waste productsproduced during drying comprising: a first dryer for partially dryingsaid matter, first means for moving said matter through said firstdryer, a first dryer fan for disposing of moisture released in saidfirst dryer, a second dryer for finally drying partially-dried matterreceived from said first dryer, said second dryer producing combustiblewaste products during the final drying of said matter, second means formoving said matter through said second dryer, said first and seconddryers being enclosed-type dryers and wherein said second dryer is ofsmaller air-handling capacity than said first dryer, said second dryerhaving an air-handling capacity in the range of about one-third toone-half of said first dryer, transfer means for transferring saidpartially-dried matter from said first dryer to said second dryer,furnace means for supplying heat to said first and second dryers, saidfurnace means maintaining inlet air temperatures in said first andsecond dryers of about 1,000* to 2,000* F. and of about 500* to 1,000*F., respectively, separating means for separating said finally-driedmatter from said waste products and for delivering the latter to saidfurnace means wherein they are consumed, and a second dryer fan fordelivering said waste products from said second dryer to said separatingmeans.
 4. Apparatus according to claim 3 wherein said furnace meanscomprises first and second furnaces for said first and second dryers,respectively.
 5. Apparatus according to claim 3 wherein said separatingmeans includes a cyclone separator connected to receive saidfinally-dried matter and said waste products from said second dryer anda conduit connected to said cyclone separator for delivering said wasteproducts to said furnace means.
 6. Apparatus according to claim 5wherein said first means for moving said matter through said first dryercomprises said first dryer fan.
 7. Apparatus according to claim 6wherein said transfer means comprises a second cyclone separatorconnected between said first dryer fan and said second dryer. 8.Apparatus according to claim 6 wherein said transfer means comprises adischarge hood connected between said first dryer and said first dryerfan and further comprises conveyor means connected between saiddischarge hood and said second dryer.
 9. Apparatus according to claim 8including a cyclone separator for receiving fines and some matter fromthe discharge outlet of said first dryer fan.
 10. Apparatus according toclaim 6 wherein said second means for moving said matter through saidsecond dryer comprises said second dryer fan.
 11. A method of drying wetparticulate matter and of disposing of waste products produced duringdrying comprising the steps of: providing a source of heat by burningcombustible fuel in a furnace means, partially drying said matter in afirst dryer heated by said furnace means by maintaining inlet airtemperatures in said first dryer in the range from about 1,000* to2,000* F. so as to extract from about 80 percent to 90 percent of themoisture to be removed from said matter, removing moisture from saidfirst dryer and discharging it to atmosphere, removing thepartially-dried matter from the first dryer and transporting it to asecond dryer which is heated by said furnace means and has a smallerair-handling capacity than said first dryer, finally drying saidpartially-dried matter in said second dryer by maintaining inlet airtemperatures in said second dryer in the range from about 500* to 1,000*F. so as to extract all but about 2 per cent to 15 per cent of theremaining moisture from said matter and producing combustible wasteproducts in so doing, removing the finally-dried matter and wasteproducts from said second dryer and separating them, and conducting thewaste products to said furnace means wherein they are consumed.
 12. Amethod according to claim 11 including the step of adding makeup air tosaid furnace means.
 13. A method according to claim 12 including thestep of tempering the heated air suppliEd to said second dryer withambient air so as to maintain air temperature in said second dryer inthe said range.
 14. A method according to claim 11 including the step oftransporting the partially-dried matter from said first dryer to saidsecond dryer to allow for equalization of the moisture in thepartially-dried matter.